A silsesquioxane derivative has an excellent heat resistance and weatherability, and therefore it is expected to be applied to a modifier for a thermoplastic resin, a interlayer dielectric, a sealing material, a flame retardant and an additive for a coating material. It has so far been tried to introduce various functional groups into silsesquioxane. Disclosed in Literature 1 is, for example, a process in which a compound having Si—OH shown below is synthesized and in which various functional groups are then introduced by reacting the compound with chlorosilanes. Disclosed in Literature 4 is a process in which a small amount of a basic compound is added when a compound having Si—OH shown below is reacted with trialkoxysilane in an organic solvent.
A in Formula (a) is the same group selected from hydrogen, methyl, ethyl, 2-methylpropyl, cyclohexyl, cyclopentyl, phenyl and vinylhexyl.
The compound represented by Formula (a) can be synthesized by hydrolyzing chlorosilane and further ripening the mixture. Disclosed by Frank J. Feher et al. in California University is, for example, a process in which cyclopentyltrichlorosilane is reacted at a room temperature or a refluxing temperature in a water-acetone mixed solvent and in which the reaction mixture is further ripened for 2 weeks (Literature 2 and Literature 3).                Literature 1: U.S. Pat. No. 5,484,867        Literature 2: Organometallics, 10, 2526-2528 (1991)        Literature 3: Chem. Eur. J, 3, No. 6, 900-903 (1997)        Literature 4: US 2003/0055193 A1        
However, in order to industrially utilize them, the compound represented by Formula (a) can preferably be produced at a higher yield for shorter time with less by-products than those of such publicly known techniques. The process in which a functional group is introduced by reacting the compound represented by Formula (a) with chlorosilane has the industrial difficulty that by-produced hydrogen chloride has to be treated. Hydrogen chloride is not by-produced in the process of Literature 4, but it requires a very long reacting time. An object of the present invention is to provide a novel synthetic process for a functional group-containing silsesquioxane derivative and a novel compound obtained by this process in order to solve these problems.